conf: Don't assign value from ..TypeFromString directly to enum
conf: Don't assign value from ..TypeFromString directly to enum

Enums are unsigned, so it's impossible to check whether the helper
returned -1 for invalid conversions.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1452454

crobinso/libvirt,jfehlig/libvirt,jardasgit/libvirt,eskultety/libvirt,VenkatDatta/libvirt,jardasgit/libvirt,VenkatDatta/libvirt,eskultety/libvirt,fabianfreyer/libvirt,datto/libvirt,jardasgit/libvirt,olafhering/libvirt,fabianfreyer/libvirt,datto/libvirt,andreabolognani/libvirt,crobinso/libvirt,andreabolognani/libvirt,olafhering/libvirt,andreabolognani/libvirt,andreabolognani/libvirt,jardasgit/libvirt,zippy2/libvirt,eskultety/libvirt,zippy2/libvirt,olafhering/libvirt,nertpinx/libvirt,jfehlig/libvirt,eskultety/libvirt,datto/libvirt,nertpinx/libvirt,nertpinx/libvirt,libvirt/libvirt,libvirt/libvirt,zippy2/libvirt,nertpinx/libvirt,VenkatDatta/libvirt,fabianfreyer/libvirt,andreabolognani/libvirt,fabianfreyer/libvirt,libvirt/libvirt,jfehlig/libvirt,jardasgit/libvirt,crobinso/libvirt,datto/libvirt,datto/libvirt,jfehlig/libvirt,eskultety/libvirt,zippy2/libvirt,olafhering/libvirt,nertpinx/libvirt,crobinso/libvirt,VenkatDatta/libvirt,VenkatDatta/libvirt,libvirt/libvirt,fabianfreyer/libvirt